@txag70 yes, my English teacher (British) told us that when he brought his then-girlfriend (Finnish) to meet his parents for the first time, his mother thought she was the rudest girl she has ever seen because she didn't shoehorn "please" or "thank you" into every sentence.

He was touring Japan (I think he was doing research on Hot Springs) and was a guest at someone's home. He ate the food, and the hostess promptly brought out more, which he ate, and more was brought out without asking.

In parts of the USA, not finishing your food implies that something was wrong with it, so it's polite to clear your plate.

@Huttj
I have been in Japan for a while and I noticed a few odd traditions. If you’re drinking with friends/coworkers/family, whenever your beer mug is getting low someone will poor you more (and you’re expected to do the same.) But I haven’t really seen this with food in restaurants. I think this is almost an outdated tradition.

HOWEVER, if you are eating at someone’s house, they will likely serve you more and more to be a good host. Honestly, though they are being nice, I find it a bit annoying sometimes. Sometimes I’ll go to someones house and they will bring out a snack and/or coffee/tea and if you don’t indulge, they will keep reminding you to have it. Again, I think it’s to be kind, but I’m not a fan.

China is very much the mind set of anything 'Public' is literally grab what you can get, it's free.
So when you 'ask nicely' for something that 'everyone owns' they just look at you weird like 'why don't you hurry up and take it already?'.
It's like asking 'excuse me, do you mind if I use this spot on the sidewalk?'.
Rather than ask, just take the spot. It's Public. It's meant for Everyone to use and abuse for Free.

In the same way, there is no 'dancing around the issue' or 'politeness' as it were. Tact is none-existent. If you dance around issues, you're seen as a coward that can't speak freely.
This unfortunately gets China viewed as Rude by others, when its as simple as a complete different form of Common Sense.

Afterall, when everyone speaks their mind and opinion strongly, in public spaces where everyone shouts to 'take the airspace', you get what's called chaos to other countries, but a normal day in China.

Plus there's the whole 'We're Friends, stop being polite, its rude'. Thing as well implied in this.
Politeness is to avoid pissing people off. Friends are meant to be able to avoid 'dancing around issues' like that. When you're not polite, when you're frank, terse, straight forward, it shows you trust the other person. You can't talk heart to heart, mind to mind, if you're constantly adding subtle additions to the things you actually want to say. Just out with it man. TALK DAMMIT. etc.

I think it is more that it implies a lack of closeness. Like, to a stranger you could say "would you be so kind as to pass the ketchup please" but speaking like that to your friends would seem weird and stand-offish.

@panthalassa That would make sense. A valid, and totally okay sentence in Danish is: "Kan du ikke lige række mig saltet?", which in a litteral translation would become: "Can't you just pass me the salt?", which does NOT sound friendly xD